Visible Bleeding is the Strongest Predictor of a Positive CT Mesenteric Angiogram in the Setting of Lower Gastrointestinal Bleeding

Aims: This study aimed to evaluate factors predictive of a positive computed tomography angiography (CTA) result in patients with lower gastrointestinal bleeding (LGIB) to guide clinical decision-making and determine which patient group has the highest diagnostic yield and which patients may be safely managed without a CTA 
Methods: This retrospective study analyzed data from 526 patients who underwent CTA at a tertiary center to investigate LGIB between 2012 and 2020. A univariate and multivariate analysis was performed to identify clinical factors outcomes associated with a positive CTA result. 
Results: The study found that patients presenting with visible bleeding on admission and requiring a blood product resuscitation were most likely to have a positive CTA result; in patients with a positive CTA, 80% required further invasive management, including angiography, transcatheter embolization, endoscopy, or surgery. There was no difference in positive CTA rates in patients taking antiplatelets, anticoagulants, or hemodynamic or severity of bleeding as defined by the modified severity index (MSI) and Oakland scores. Patients with a positive CTA had a shorter time to CTA from the last episode of LGIB than those without a blush, supporting the notion that sensitivity is improved with the expediating timing of CTA.  
Conclusions: CTA is an effective first-line diagnostic tool in severe acute LGIB. This study highlights the clinical utility of CTA in patients with LGIB, stressing the need for judicious and efficient use of CTA. Medical and conservative management should be prioritized for patients without a negative CTA. Patients with a positive CTA are highly likely to require further invasive intervention and should be transferred to a tertiary center capable of providing these services.